Photochemical lamp base



Oct. 30, 1956 G. w.l cAPLls E11-AL y 2,769,156

PHoTocHEMIcAL LAMP BASE Filed Jan. 24, 1955 United States Patent OPHOTOCHEMICAL LAMP BASE George W. Caplis, Preakness, Vernon L. Plagge,East Orange, and Frank J. Hierholzer, Jr., Bloomfield, N. J., assignorsto Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application January 24, 195i5, Serial No.483,5(12

1 Claim. (Cl. 339-145) The present invention relates to tubular electriclamps with bases at both ends, such as photochemical lamps and, moreparticularly, to an improved base for such a lamp.

We are aware on U. S. Patent 2,515,747 issued July 18, 1950, to DanielI. Vaughan and assigned to the General Electric Company. This patentrelates to a photochemical lamp base of the prior art type. The presentinvention provides a novel and improved lamp base.

This patented base may comprise a body portion of insulating material,such as porcelain, secured to a metal skirt by means of an enlargedshoulder on the body portion. A thin strip of asbestos paper moistenedwith a solution of sodium silicate is secured about the lamp envelopeprior to the slipping of the slotted end of the skirt over the end ofthe lamp envelope. The skirt is secured iinnly in place about the lampenvelope by a clamping collar. The skirt is tightly secured to the bodyportion by a split metal snap ring which is forced against the side ofthe shoulder of the body portion by four ring retaining dimplesequi-spaced about the inner wall of the skirt. These ring retainingdimples because of their location on the shoulder engaging portions ofthe skirt are most di'icult to form.

Relative rotary displacement between the body portion and the skirt isprevented by the insertion of a plurality of equi-spaced dimples in theskirt into a like number of longitudinal slots provided in the peripheryof the shoulder of the body portion. The diiiculties in making porcelainbodies to close tolerances is well known in the art. Although themetallic skirts and hence the snap ring retaining dimples therein may belocated to close tolerances, variations in the shoulder of the porcelainbody portions often produce an unsatisfactory base. A long shoulderprevents the snap ring from being securely anchored by the retainingdimples. A short shoulder provides considerable longitudinal movementbetween the skirt and the body portion.

In addition, the patented base is assembled by machine. This automaticassembly results in mechanical impact on the brittle porcelain body ofthe base and considerable assembly shrinkage.

Hence, it has been found advantageous according to the invention toprovide an improved base for a photochemical lamp which eliminates useof the snap ring and the four snap ring retaining dimples of the priorart design. The improved base of our invention has substituted an excessof a high temperature cement for the mechanical snap ring holdingfeature of the patented base. Again, our base incorporates a snap-litlocking feature which automatically provides a positive cement bond (thevariable compensating factor) between skirt and body and insures acontinued bond `in the event of cement failure in service. This snap fitfeature (the fixed compensating factor) comprises a bent-in locking tabin the base skirt for engagement with a radial locking slot in the topof the lamp base body to prevent relative vertical or rotary lateralmovement of the parts. An excess of the high temperature heat resistantcement is placed between the skirt and the porcelain body and isproperly compressed or positioned with respect thereto until the tabssnap into the slots in the body, so that the cement lls the voidsbetween the skirt and body and the excess of cement ilows therebetween.Further, the locking tabs on either side of the skirt, now in engagementwith the bottom wall of the radial tab slots in the shoulder of theporcelain body, provide an added safety locking feature if the cementbond fails under abnormal service conditions of excessively hightemperature.

In its general aspect the present invention has as its objective animproved base for a photochemical lamp which eliminates the snap ringand the plurality of snap ring retaining dimples normally provided inthe skirt of said base.

A specific object of the present invention is an excess of a hightemperature cement between the porcelain body and the metallic skirt andwhich fills the voids therebetween.

An additional object is a base having a snap-in locking featurecomprising bent-in locking tabs on the skirt which snap in against thebottom wall of radial locking slots provided in the top portion of thebody, thus insuring a complete positive cement fill between the skirtand the body and adequately insuring a continued tight connectionbetween the skirt and the body in the event of high temperature failureof the cement in service.

An additional object is an improved base for photochemical lamp having avariable compensating factor, an excess of cement, and a fixedcompensating factor, a

p snap-in feature, which permits relatively larger tolerances in thedimensions of porcelain body of said base and yet prevents loosephysical connections between the skirt and porcelain body of said base.

An additional object is an improved photochemical lamp base providedwith a high temperature air drying heat resistant cement between themetal skirt and porcelain body to provide a tight connectiontherebetween and thus insure the proper mounting of the photochemicallamp in a lighting fixture.

Other objects of the invention will become apparent to those skilled inthe art to which it appertains as the description proceeds both bydirect recitation and by implication from the context.

Fig. l is a side elevational View of an improved base of the inventionand showing said base in vertical section and secured about an electriclamp having a tubular envelope, such as a photochemical lamp.

Fig. 2 is an enlarged fragmentary view showing the cement bond between ametallic skirt and a body of insulating material of said base andshowing the insurance locking feature therebetween.

Fig. 3 is a horizontal sectional view of the base and lamp along theline III-III of Fig. l in the direction of the arrows and showing thesnap-lit locking slot provided in the top face of the shoulder of thebody'.

Fig. 4 is an exploded perspective view of the insulated body, metalliccollar, and mounting or holding collar of the improved base of theinvention.

Referring now to the drawings in detail and particularly to Fig. 1 thereference numeral 10 designates an electric lamp having an elongatedtubular envelope 12. This envelope 12 may be provided with a base 20 ofthe invention at either end for engaging suitably spaced sockets (notshown). The envelope 12 may have an electrode mount 22 sealed to eachend thereof and connected to the lamp base 20 of the invention by meansof a flexible lead-in conductor 24.

The improved base 20 of the invention has a hollow body 26 of insulatingmaterial, such as porcelain. This body 26 may be provided with a hollowmetallic contact prong 28 which extends axially outwardly from the body26, and Vis connected to the outer end of the flexible leadin conductor24, as by crimping at 30. The other end of the body 26 is provided withan enlarged arcuate shoulder 32.

A metallic skit 34 is secured about said shoulder 32. As shown in Figs.3 and `4, the upper portion of the body 26 is provided with insurance(locking) snap-'in slots 36, suitably diametrically disposed andmetallic skirt dimples slots 38 juxtaposed 90 from the snap-in slots 36.

As shown particularly in Fig. 4, the right ha-nd periphery of skirt 34of the base 20 is provided with a multiplicity of suitably parallelslits 40 to form tines or prongs 41. These tines 41 may be readilycompressed by clamping a base mounting collar 42 about a suitableasbestos strip 43 (Fig. 1) wrapped about the lamp envelope 12. The lefthand end (when viewed in Figs. l and 4) of `this skirt 34 is desirablycontoured into an integral flange to t about the shoulder 32 of the body26 with a cement 50 therebetween. Relative rotary displacement betweenthe body 26 and the skirt 34 is prevented by a plurality of dimples 44,for example, two are shown in Fig. 3 which are suitably diametricallydisposed for engagement with rotary locking slots 38 in the periphery ofthe shoulder 32 of the body 26. Bent-in locking tabs 46 provided in theskirt 34 (Fig. 4), suitably 90 from the dimples 44 therein, engage thebottom wall of the locking slots 36 provided in the body 26.

A suitable air drying heat resisting cement 50 such as lnsa-lute cementNo. l may be employed. Insa-lute cement No. l is a trade name for an airdrying white adhesive cement having the consistency of heavy cream.Insa-lute cement No. 1 is manufactured by the Sureisen Cement Co. ofPittsburgh, Pa. lt is an electrical insulating and heat resistant cementwhich resists acids, ternperatures up to 1093 C. (2000 F.) and oils andtire.

Assembly of the base As shown particularly in Fig. 4, lthe body 26 ofthe base 20 having the lead-in conductor 24 crimped to the contact 28 isprovided with a suitable excess coating of cement t) on the outsidethereof and is inserted prong rst into the metallic skirt 34 so that theleft hand shouldered end (when viewed in Fig. 4) of the skirt 34 restsagainst the excess cement 50 on the shoulder 32 of the body 26. Theshoulder 32 on the body 26 has forced the resilient tabs 46 outwardlyfrom their normal locking position. The skirt 34 is rotated on the body26 until the dimples 44 in the skirt 34 engage the displacement slots 3Sprovided in the periphery of the shoulder 32 of the body 26. it will beunderstood that when the dimples 44 engage the slots 38 that the snap-intabs 46 in the skirt 34 are positioned to register radially with theinsurance locking snap-in slots 36 of the body 26. The body 26 and thecement 50 is then compressed, as by hand, against the skirt 34 (with theexcess cement forced therebetween) until the tabs 46 snap into the slots36 and frictionally engage the bottom wall thereof. v

It will be understood that these resilient tabs 46 are prebent to swinginwardly and frictionally engage, or scrape, the bottom of the slots 36in the body 26, thereby providing an added positive safety lockingfeature which prevents lateral and vertical movement between the body 26and the skirt 34, if the cement 50 fails under abnormal serviceconditions.

The upper end of the flexible leading-in conductor 24 is then secured,as by welding, to the electrode mount 22 of a photochemical lamp 10. Theenvelope` 12 is inserted into `the base 20 of the invention so that thetines 41 of the skirt 34 engage the strip 43 of asbestos papermoistened, for example, with a solution of sodium silicate and wrappedaround the skirt engaging portions of the envelope 12. The adjustment ortightening bolt on the collar 42. may then be tightened so that the base20 is securely affixed to the envelope 12 of the lamp 10.

Thus it will be seen from the foregoing description that we haveprovided an improved base 21B for a photochemical lamp l@ whicheliminates the use of a snap ring and a plurality of snap ring retainingdimples in the skirt of the prior art base. We have employed an excessof a high temperature cement 50 (as a variable compensating factor) toll the voids between the (loose tolerance) porcelain body 26 and themetallic skirt 34 of the base 20 and to provide a tight connectionbetween the skirt and the body. Further, we have provided a base 2i)having an insurance snap-in locking feature comprising bent-in lockingtabs 46 (as a iixed compensating factor) on the skirt 34 which snapfrictionally inwardly against the bottom wall of radial locking slots 36provided in the top face of the body Z6 to provide a tight connectionbetween the skirt 34 and the body 26 and to insure adequate mounting ofthe lamp 10 in its socket. Through the useV of excess cement 50 betweenthe skirt 34 and the body 26 we are able to employ loose tolerances inthe dimensions of the porcelain body 26 and still provide a positivephysical connection between the skirt 34 and the body 26. Our hightemperature air drying heat resistant ccment 50 between the skirt 34 andthe body 26 provides a tight connection therebetween and insures theproper mounting of the photochemical lamp 10 in suitable lightingiixtures.

Although a preferred embodiment of our invention has been described itwill be understood that modifications may be made within the spirit andscope of the invention.

We claim:

A base for a double ended tubular electric lamp comprising a loosetolerance hollow tubular body of electrically insulating material andhaving a circumferential shoulder at one end, said shoulder beingprovided with a plurality of radial snap-in locking slots in the upperportion thereof, a metal skirt overlapping and secured to said shoulderand having a like number of bent-in locking tabs for frictionallyengaging the bottom of said slots to iixedly compensate for variationsin the dimensions of said body and to positively hold said body and saidskirt against relative rotary and longitudinal displacements, and hightemperature cement completely filling the voids between said body andsaid skirt to variably compensate for variation in the dimensions ofsaid body and to insure said frictional engagement of said tabs with thebottoms of said slots. i

.Vaughan July 18, 1950 2,538,609 Watrous July 16, 1951 2,692,154 WiganOct. 19, 1954

